People have dinner at restaurants in Washington, D.C., the United States, Aug. 7, 2020. (Xinhua/Liu Jie)

"Initial jobless claims unexpectedly rose to 1.1M as the labor market's recovery remains precarious," U.S. senior economist Sarah House said.

WASHINGTON, Aug. 20 -- The number of initial jobless claims in the United States rose back above the 1 million mark last week, casting shadow on the recovery of a labor market ravaged by the COVID-19 crisis.

In the week ending Aug. 15, the number of Americans filing for unemployment benefits increased by 135,000 to reach 1.1 million, the Labor Department said in a report on Thursday.

"Initial jobless claims unexpectedly rose to 1.1M as the labor market's recovery remains precarious," Sarah House, senior economist at Wells Fargo Securities, wrote in an analysis.

As COVID-19 shutdowns rippled through the workforce, initial jobless claims spiked by 3 million to reach a record 3.3 million in the week ending March 21, and then doubled to reach a record 6.87 million in the week ending March 28.

After that, the number had been declining for 15 weeks consecutively -- though they were still at historically high levels -- before the trend was reversed in the week ending July 18 amid a resurgence in COVID-19 cases.